About 1140 he was back in Paris, studying theology and supporting himself by tutoring the sons of nobles, sharing an apartment with Peter of Celle, who became a Benedictine and abbot of St. Rémy at Reims. While attending the Council of Reims in 1148, it is believed he was introduced by Bernard of Clairvaux to Theobald of Bec, the Archbishop of Canterbury. John became Theobald's secretary.
This position brought him back to England, where he was secretary to Theobald for seven years and where he came to know Thomas Becket. John also made trips to Rome during this time, where he got to know Nicholas Breakspear, the only Englishman to become pope (as Adrian IV).
In 1176, John was made Bishop of Chartres, a position he held until his death on 25 October 1180. His successor as bishop was his longtime friend and former roommate in college, Peter of Celle.
Now that we have some background on the man, we'll turn next to his written works.